lwiay means "last week i asked you". It's invented by the youtuber PewDiePie (sorry Jacksfilms) and is a name for a youtube-serie where the youtuber reacts to submissions from their fans.
It stands for: Last week you asked. It's an intro of Felix (aka. PewDiePie) series where people post their stuff on reddit and Felix would react to it. Its almost copied from Jackfilms and his series. That's the joke.
"Leave your entries in the subreddit bros and I'll watch submissions in the next episode of LWIAY"
LWIAY - Last Week I Asked You (Name of PewDiePie’s rubric on his YouTube channel, in which he reviews some stuff, which was sent to him by his subscribers)
